1. Field of the Invention
This invention relates to bending brakes and more particularly to a combination cleat bender and bar folder apparatus.
2. Description of the Prior Art
The bending brake devices of the prior art are, in general, adapted to form sheet metal into a variety of shapes by a series of bending or folding operations. The simplest form of apparatus involves a pair of clamping jaws to secure a sheet metal workpiece and a bending brake adjacent the clamping means or jaws which is adapted to contact a portion of the sheet metal protruding therefrom to rotate the metal in a bending action around a pivot point adjacent the terminus of the jaws. The conventional apparatus of the prior art is so constructed so that the bend achieved is usually no greater than 90.degree., or in other words, essentially a right angle bend, which may be exemplified by U.S. Pat. No. 3,380,280 issued to Wise on Apr. 30, 1968. This patent discloses a pair of spaced apart, rigid frame members, one of which carries a brake platen securely fastened thereto and the other having a clamping table mounted thereon. The table is adapted to move between an open position relative to the braking platen and a closed or clamping position. The table also carries an elongated brake bar and a hinge means supporting the brake bar on the table for pivotal movement about an axis substantially coextensive with the fixed braking edge when the table is in the braking position. The apparatus, while capable of making 90.degree. bends, is not capable of making 180.degree. bends since the bending action of the brake bar is limited by the shape of the forward edge of the brake platen which holds the sheet metal workpiece.
More complex cleat benders may be exemplified by U.S. Pat. No. 3,731,514, patented on May 8, 1973. This patent discloses a cleat bender and a pair of punch means traveling at substantially right angles to each other, adapted to form the metal into a U-shaped configuration around the free end of the forming die which is an integral part of the table surface. The U-shaped configuration is achieved by making essentially two spaced apart 90.degree. bends on separated portions of the workpiece by folding the same around a square-ended die.
Summer, U.S. Pat. No. 3,552,176, patented Jan. 5, 1971, discloses an apparatus for folding the end portion of a metal sheet to a somewhat larger angle than 90.degree., preferably an angle in excess of 135.degree.. The apparatus including a single folding rail which has a nose portion and an inclined surface portion. The movement of these elements is so controlled that the nose portion folds the sheet metal end by 90.degree. and subsequently the inclined surface portion additionally folds the thus folded end portion beyond 90.degree. to the desired folding angle. The second folding action takes place by movement of the folding rail against a surface of the lower holding jaw which inclines rearwardly from the first folding edge wherein the 90.degree. bend is formed. The angle of the fold is limited by the necessary structure of the lower jaw to achieve the strength necessary to form a supporting surface. Neither Summer nor any of the other prior art apparatuses are capable of forming a bend in sheet metal which is 180.degree. or more. Moreover, most of the prior art constructions are not adapted to form combination bends or complex shapes on the bending machine. Furthermore, the apparatuses of the prior art were incapable of forming complex bends on structures such as ducts which are not in the flat sheet form.